Current-sensing resistor design to include current derivative in PWM H-bridge unipolar switching power amplifiers for magnetic bearings

To effectively reject the influence of digital control delay on system bandwidth and stability in pulsewidth-modulation H-bridge unipolar switching power amplifiers for magnetic bearings and to overcome the disadvantages of the traditional linear predictive control, this paper presents a current-sensing resistor design to include current derivation. The proposed solution can realize predictive current control by the proportional-differential current-sensing resistor networks. The common problems associated with the digital control delay are successfully resolved by the proposed method. Moreover, compared to the traditional linear prediction, the proposed one not only shortens the calculation time of the digital signal processor but also increases the tracking precision and significantly reduces the current noise. Analysis, simulation, and experimental results are presented to demonstrate the effectiveness and superiority of the proposed method.